In an image forming apparatus such as laser printers, there is known a developing cartridge that is detachably mounted to a main body of the apparatus.
The developing cartridge includes a developing roller and a supply roller that supplies toner to the developing roller. When the developing cartridge is mounted to the main body, the developing roller contacts a photosensitive drum that is provided in the main body. When forming an image, a bias having the same value is supplied to the developing roller and the supply roller, for example. When an electrostatic latent image formed on the photosensitive drum is opposed to the developing roller in accordance with rotation of the photosensitive drum, toner is supplied to the electrostatic latent image from the developing roller by a potential difference between the developing roller and the photosensitive drum. Thereby, the electrostatic latent image is developed as a toner image. Then, the toner image is transferred to a sheet, so that an image is formed on the sheet.
In order to improve an image quality, it is considered to individually set the bias that is supplied to the developing roller and the supply roller. In this case, it is required to provide electrodes individually to the developing roller and the supply roller and to configure them such that contact point members, which are provided to the main body in correspondence to the respective electrodes, contact the respective electrodes when the developing cartridge is mounted to the main body.
There has been proposed a related art developing cartridge in which electrodes are respectively provided to a developing roller and a supply roller, and a first contact point member and a second contact point member, which are electrically connected to a rotation shaft of the developing roller and a rotation shaft of the supply roller, respectively, are provided in a cover member that covers end portions of the developing roller and the supply roller. The first contact point member and the second contact point member are respectively extended toward positions away from the developing roller and the supply roller. Each leading end of the first and second contact point members is bent into a substantially U shape and is exposed as a contact point part (electrode) through each of openings that are arranged at the cover member in an upper-lower direction.